. A textbook of botany for colleges and universities ... Botany. REPRODUCTION AND DISPERSAL 8ll amoeboid movements; much more characteristic are non-motile car- pospores and tetraspores (figs. 150, 151), which, like zoospores, are devoid of protective walls. Non-motile spores may occur also in the green algae (as in the aplanospores of Botrydium, fig. 93). Asexual spores in the fungi. â⢠Perhaps the culmination of asexual spore development occurs in the fungi. A few forms that grow in water or in wet places have ciliated zoospores (as in Saprolegnia, fig. 156); in certain myxomycetes there ar
. A textbook of botany for colleges and universities ... Botany. REPRODUCTION AND DISPERSAL 8ll amoeboid movements; much more characteristic are non-motile car- pospores and tetraspores (figs. 150, 151), which, like zoospores, are devoid of protective walls. Non-motile spores may occur also in the green algae (as in the aplanospores of Botrydium, fig. 93). Asexual spores in the fungi. â⢠Perhaps the culmination of asexual spore development occurs in the fungi. A few forms that grow in water or in wet places have ciliated zoospores (as in Saprolegnia, fig. 156); in certain myxomycetes there are zoospores which swim for a time, and then lose their cilia and creep with an amoeboid movement. In general, however, fungus spores are not self-motile, and are invested with con- spicuous walls. They may be borne within a special spore-bearing organ, for example, a spo- rangium (as in Mucor, fig. 1122), or an ascocarp (as in Peziza, figs. 175, 176), or they may be developed externally, as in the conidia of Peni- cillium (fig. 179) and in basidiospores 'â (fig. 201). Fungus spores commonly are dispersed by wind, and their minute size and their resistance to wetting make possible the remarkable effi- ciency of this agent; even the very slightest movements of the air are suflacient to initiate dispersal. Many species of fungi are common to widely separated regions, and it is thought that this cosmopolitanism is due in large part to the effectiveness with which their spores are dis- persed by wind. The abundance of spores and the ease with which they are carried is shown by the readiness with which cultures of various fungi may be made anywhere by exposing to the air, bread or cheese, properly moistened, so as to insure good conditions for germination. Fungi surpass all other plants in the number of new individuals that may be produced from a single plant by asexual spores. A single large puffball (as Lycoperdon giganteum) may produce several trillion spores, and in other lar
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